Configuration for vertical take-off and landing system for aerial vehicles

ABSTRACT

A vehicle, includes a main body. A fluid generator is coupled to the main body and produces a fluid stream. At least one tail conduit is fluidly coupled to the generator. First and second fore ejectors are coupled to the main body and respectively coupled to a starboard side and port side of the vehicle. The fore ejectors respectively comprise an outlet structure out of which fluid flows. At least one tail ejector is fluidly coupled to the tail conduit. The tail ejector comprises an outlet structure out of which fluid flows. A primary airfoil element includes a closed wing having a leading edge and a trailing edge. The leading and trailing edges of the closed wing define an interior region. The at least one propulsion device is at least partially disposed within the interior region.

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Appl. No.62/525,592 filed Jun. 27, 2017, the contents of which are herebyincorporated by reference as if fully set forth herein.

COPYRIGHT NOTICE

This disclosure is protected under United States and/or InternationalCopyright Laws. © 2018 Jetoptera, Inc. All Rights Reserved. A portion ofthe disclosure of this patent document contains material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and/or Trademark Officepatent file or records, but otherwise reserves all copyrightswhatsoever.

BACKGROUND

Every VTOL aircraft faces the challenges of sizing of the engine(s) andthe balance of forces. See Daniel Raymer, Aircraft Design: A ConceptualApproach (AIAA Education Series), page 754 (5th ed. 2012).

Vertical take-off can be achieved with a high thrust-to-weight ratio. Incontrast, during horizontal flight (cruise), lift forces contribute tothe aircraft, and the thrust requirements are much smaller. However, ifthe intent is to design an aircraft that flies horizontally for a periodof time, the VTOL requirement would make the engine requirements toolimiting, adding a lot of weight that is then carried around in cruiseconditions without functionality. Therefore, the sizing of the engineand thrust matching for a cruise-dominated VTOL aircraft becomes a majorissue.

Balance is one of the most important drivers for the design of a VTOLaircraft. During the take-off phase, the thrust has to be distributedaround the aircraft, and moments are balanced around the center of mass,in order for the aircraft to remain balanced. The aircraft cannot bebalanced if the source of the thrust is in only one location. Forexample, even when a horizontal aircraft such as the Harrier is balancedin air, the aircraft needs to employ several thrust generating elementsin locations specifically chosen in order to cancel out the moments atall times (calculated as force (thrust)×moment arm around the center ofthe aircraft mass). This is difficult to achieve if the majority of thethrust is located, for instance, in the rear portion of the aircraft (astypically found in a VTOL aircraft).

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates a top view of an embodiment of the present invention;

FIG. 2 is a rear view of the embodiment of the present invention shownin FIG. 1;

FIG. 3 is a front view of the embodiment of the present invention shownin FIG. 1;

FIG. 4 illustrates an alternative embodiment of the present invention inan exploded isometric view;

FIG. 5 illustrates an alternative embodiment of the present invention inrear perspective view;

FIGS. 6A-6D illustrate the progression of an embodiment of the presentinvention from take-off to level flight relative to a landing/takeoffsurface; and

FIG. 7 illustrates the upper half of a turboshaft/turboprop engine withhighlights of the stations of the flow according to an embodiment of thepresent invention

FIG. 8 illustrates one embodiment of the present invention in a topview.

FIG. 9 is a side cross-sectional view of the embodiment shown in FIG. 8.

FIG. 10 is a front view of the embodiment shown in FIG. 8.

FIG. 11 is a rear view of the embodiment shown in FIG. 8.

FIG. 12 is a top view of an alternative embodiment of the presentinvention.

FIG. 13 is a side cross-sectional view of the embodiment shown in FIG.12.

FIG. 14 is a front view of the embodiment shown in FIG. 12.

FIG. 15 is a side cross-sectional view of the embodiment shown in FIG. 8during the take off to cruise transition.

FIG. 16 illustrates the cruise position of the embodiment shown in FIG.8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This application is intended to describe one or more embodiments of thepresent invention. It is to be understood that the use of absoluteterms, such as “must,” “will,” and the like, as well as specificquantities, is to be construed as being applicable to one or more ofsuch embodiments, but not necessarily to all such embodiments. As such,embodiments of the invention may omit, or include a modification of, oneor more features or functionalities described in the context of suchabsolute terms. In addition, the headings in this application are forreference purposes only and shall not in any way affect the meaning orinterpretation of the present invention.

The present application relates generally to thrust augmentation forunmanned aerial vehicles. In particular, one or more embodiments of thepresent invention disclosed in this application provide unique solutionsto the challenges of vertical take-off and landing (VTOL) and shorttake-off and landing (STOL) aircrafts. As used herein, the terms“Tailsitter” and “Flying Vehicle” may refer to one or more embodimentsof the present invention.

An embodiment of the present invention addresses the issue ofthrust-to-weight ratio and sizing of the engine through enhancing andaugmenting the thrust. In a preferred embodiment of the presentinvention, the ejectors/thrusters themselves are designed to allow foraugmentation exceeding 2:1 and close to 3:1. This means that thesethrusters are designed to produce a thrust that is 2-3 times greaterthan the thrust produced by a conventional turbojet. Thrust augmentationdesigns are disclosed in U.S. patent application Ser. No. 15/221,389,entitled FLUIDIC PROPULSIVE SYSTEM, filed Jul. 27, 2016 (“the '389Application”) and U.S. patent application Ser. No. 15/256,178 filed Sep.2, 2016 (“the '178 Application”), each application of which is herebyincorporated by reference as if fully set forth herein. As used herein,“thrusters” shall refer to such ejectors/thrusters with significantaugmentation that are described in the '389 Application as well as anysubsequent versions or improvements thereof.

In a preferred embodiment of the present invention, the Thruster is usedwith a gas generator as a source for primary flows. While it is notnecessary to utilize such a Thruster with a gas generator that suppliesthe primary flow in the present invention, utilizing such a Thruster canenhance the effects of thrust augmentation.

Further augmentation can be achieved through a secondary, major ejectorthat can be formed by using the exhaust from the Thrusters inconjunction with, for example, a closed/box wing of the Tailsitteracting as a shroud. The wings may also take any other shape that isdesigned in such a way to allow the high-speed exhaust of the Thrustersto serve as primary nozzle for the ejector formed by the wing (“shroud”)and Thrusters. The effects of the shroud can further augment the thrustby at least 10-25%. In effect, the Thrusters and the shroud can have acombined effect of thrust augmentation of, for example, 1.1 (fromshrouded thrusters) times 2.5 (from Thrusters) augmentation, whichresults in a total augmentation of 2.75. Therefore, such a system canproduce a thrust that is equal to the weight of the aircraft at takeoffby augmenting an otherwise ˜2.75 thrust generated by a simple turbojet.

In any aircraft which takes off vertically on its tail, the aircraftwould naturally need to adjust its attitude to level off at theacceptable attitude and reduce its thrust in order to keep the aircraftflying forward at a constant cruise speed. Thrust reduction via throttlereduction may adjust the power needed to overcome the drag of theaircraft, which may also mean a lesser augmentation of the entire systemand sufficient to propel the aircraft forward and maintain its speed.

In one embodiment of the present invention, a 150-lbs aircraft mayemploy a 75-lbf turbojet adapted to become a gas generator. This conceptis disclosed in U.S. Provisional Patent Application 62/263,407, entitledMICRO-TURBINE GAS GENERATOR AND PROPULSIVE SYSTEM, filed Dec. 4, 2015(“the '407 Provisional Application) and U.S. patent application Ser. No.15/368,428 filed Dec. 2, 2016 (“the '428 Application”). The '407Provisional Application and '428 Application are herein incorporated byreference in their entireties. In this embodiment, these thrustaugmenting ejectors can produce an augmentation of, for example, 1.75times the original, which means 75 multiplied by 1.75, which results in131.25 lbf augmented thrust. Without a shroud around the Thruster, thethrust may be limited to this value and may not allow the thrust to liftthe aircraft off the ground. However, with a wing such as a boxedstructure around the main Thruster(s) to shroud these Thrusters, theoverall augmentation of the thrust becomes, for example, e.g., 1.15multiplied by 131.25, resulting in 150.94 lbf, and hence exceeds theweight of the aircraft and allows for the take-off.

As the fuel is consumed on board the Tailsitter, the weight of thevehicle becomes lighter and the acceleration of the vehicle becomeslarger, so the take-off happens at increasing speed and acceleration.Because the vehicle may not be inhabited, the accelerations may exceedthe current human-limited accelerations that are restricted for humansafety and non-life threatening standards. In one embodiment, theaccelerations may exceed 20 times the gravitational acceleration. Assuch, after a short time, the vehicle may have the ability to change itsattitude and achieve level flight by throttle and control surfacechanges. Lift increases as the vehicle changes its attitude, while thecombined augmentation also diminishes in value due to the throttle pullback. The Tailsitter may then achieve level flight by concomitantlyreducing the engine load (ergo gas generator primary stream) to thethrusters in the first level and allowing the boxed wing to produce theproper lift to maintain the attitude, while the thrusters produce enoughthrust to overcome drag.

Conversely, on approach to the destination, the attitude of the aircraftcan be adjusted with an increase angle of attack and the thrustaugmentation again displaces the need for lift, as the forward speedreduces and the aircraft eventually can land vertically, on its tailportion, balanced by the thrusters and its combined augmentation effect.

One or more embodiments of the present invention are able to overcomethe issue of balancing the forces and moments by having smaller momentarms than are needed to balance them around the center of mass, which isachieved by having a distribution of thrust across various locations inthe aircraft. This, in turn, allows these embodiments to have morecontrol and makes it easier to maintain a hover/upright position.

As discussed in the '389 and '407 Applications, the unique technologyallows for the distribution of thrust across various locations of theaircraft, with augmentation levels achieved in various thrusters (e.g.,in front, “fore ejectors” behind canard wings, employed at hoveringphases take-off and landing and turned off at level flight, and in theback the “tail ejectors” that generate the bulk of the thrust).

A conventional small (<250 lbf thrust) mini jet engine usually providesthrust at a single location, typically at the center of the exhaustsection. Some small turbofans also provide the thrust in a concentratedpoint on the aircraft. One or more embodiments of the present inventionallow the distribution of the thrust in a nearly linear and/ornon-circular manner, as opposed to a circular manner, and thusdistribute the thrust per the length of a wing or other airfoils and/orcontrol surfaces of an aircraft. In the Tailsitter, both the main, hotstream and the bleed air portion of the stream from the compressor areused as motive fluids for the augmenting thrusters. Because thisembodiment allows the distribution of the thrust in a linear, mainlynon-circular and distributed, not at a concentrated point, it achievesbetter propulsive efficiency of the aircraft. In addition, there is theoptionally advantageous feature of molding and shaping the thrusteraccording to the shape of the airfoils to obtain better performance(e.g., increasing the stall margin of a given canard wing if thruster isplaced downstream of it, or augmenting the lift on a main wing if thethruster is placed at an optimal location upstream of said main wing).The distributed thrust therefore improves the performance of theaircraft by distributing an otherwise 75 lbf turbojet hot and faststream from a concentrated location at the back of the turbojet engineto, for example, at least four locations on the aircraft. In thisexample, thrusters are mounted at these four locations on the vehicle inan optimal manner, such that they are (i) receiving the pressurized airor gas stream from the compressor bleed system and exhaust of the gasgenerator respectively and (ii) augmenting each of the four thrustforces that would otherwise result from the simple isentropic expansionof the four primary streams by 1.5-3 times. This also results in anadvantageous distributed flow and thrust from the four locations, thusenhancing the aircraft maneuverability and propulsive efficiency.

An embodiment (a turboprop STOL version) of the present inventionincludes augmentation of thrust based on motive fluid provided by ableed system of a gas generator. The bleed system provides the port andstarboard front thrusters with the motive air from the bleed. The frontthrusters provide an augmentation corresponding to specific thrust of100-300 lbf for each lb/sec of motive air provided by the bleed system.This value exceeds by far the typical 50-65 lbf/lb/sec specific thrustobtained with small turbojet engines, due to limited efficiencies of thecomponents and lack of advanced technologies. When turned into a gasgenerator, the value of the compressed air is utilized by employing thethrusters in front and back of the system resulting in augmentationratios of over 2:1. As such, more thrust can be obtained from the sameenergy input.

In such an embodiment, a control valve is employed to provide thebalance of flow between the port and starboard thrusters. The modulationof the air can be obtained with valves placed between the engine bleedand the control valve box. The valves allow for control of the flow oneach thruster and/or balance of the flow of the motive air between thetwo front thrusters by opening or closing a passage to one or both ofthe front thrusters and changing the motive fluid supply. This, in turn,generates an imbalance in thrust, and the imbalance results in thechange in the aircraft attitude. The thrusters can also be swiveledaround their main axis, while being modulated for primary flow (motivefluid flow) at the same time. This allows for control on the pitch androll as well as some limited control on the yaw, and combinationsthereof.

In an embodiment, thrusters are supplied a high pressure hot stream ofexhaust gas delivered by the generator (minus the bleed air) via atransition piece or conduit. The transition piece connects the exhaustof the gas generator to the said rear thrusters. Thrusters use thisdelivery as a motive air to augment the thrust. This jet augmentingsystem is specifically designed to allow fast movement of the vehicle atthe cost of additional fuel consumption, resulting in airspeeds of thevehicle exceeding 200 MPH and propulsive efficiencies of close to80-90%. The system results in a typical specific fuel consumption of0.8-1.1 lb/hr of fuel per lbf generated, which is typical of the lowby-pass fans, but without a fan or turbine driving the fan. These levelsare much more performant than the typical 1.5 lb/hr per lbf usuallyobtained with small turbojets, the majority of the current markets fordrones. The system can also achieve the performance of specific fuelconsumption of a low-bypass turbofan at much smaller scale and withoutemploying a free turbine and a fan, per se, reducing thus the weight andcomplexity of the entire propulsion system and eliminating a large,moving assembly such as the fan/free turbine assembly.

In an embodiment, if the mission of the aircraft is longerduration/range and slower airspeeds at higher propulsive efficiencies,then the rear section of the propulsive system can be made flexibleenough to be replaced by a turbine/propeller system while keeping thecommon, identical gas generator (front of the propulsive system) andaugmenting “cold” thrusters. The turbine will receive the same flow asin the case of the jet augmenting system, but can extract the energyfrom the gas generator exhaust flow and turn it into mechanical workused to rotate the propeller rather than fluidically augment the flow inan ejector type thruster. The interfaces are very similar, thereplacement consisting of the removal of the transition piece conduitwith a conduit that guides the hot, pressurized gases towards the freeturbine driving the propeller, after which the exhaust gases areexpelled in the downstream direction and into the wash of the propeller.The advantage of such a flexible system is that with the similararrangement, a turbopropeller pusher or a jet augmenting system can beinterchangeable, allowing the user to choose the system based on themission at hand. As such, a turbopropeller pusher system as describedcan achieve a specific fuel consumption level of below 0.6 lb/h per eachhorsepower or equivalent thrust lbf achieved. In one embodiment of thepresent invention, the UAV may be able to deliver a parcel as far as 200miles away moving at an average cruise speed of 150 mph.

Furthermore, the propeller can be perfectly contained by, for example,the box wing system described herein, and thus the noise generated bythe turboprop can be significantly reduced by direct (box wing) andindirect means (noise abatement materials inside the wing). In addition,the turboprop still benefits from the presence of the front thrustersand the use of bleed air to power them, allowing not only VTOL but whereappropriate and VTOL not necessary, short take-off and landing.

In one or more embodiments of the present invention, the short take-offand landing (STOL) concept can be achieved by the employment of thefront thrusters, significantly lowering the runway length required fortake-off. By swiveling the thrusters, additional vectored thrust can beoriented to increase pitch during take-off and reduce the length neededas compared to a conventional aircraft. The front thrusters may be shutoff during cruise or loitering, or re-activated at various stages of theflight, to augment lift, or thrust or both. The augmentation of thethrust can be accomplished through the very design of the thrusters. Theaugmentation of the lift can be accomplished by the placement of thefront thrusters in relation to both the canard (front wings) and themain box wing. The downstream location of the front thrusters delaysstall of the canard wings, allowing operation at higher angles of attackand higher lift coefficients before stall occurs. This is due to thelower pressure created in front of the thrusters, delaying theseparation on the top of the wing, the main cause of stall on most wingsat high angles of attack. The lift augmentation due to the main wing ismainly due to the increased flow resulting from the front thrusters,locally higher than the airspeed of the vehicle, which said flow isguided over the bottom part of the box wing and, as known to thosefamiliar with the matter, augmenting the lift of the main wing.

FIGS. 1-3 illustrate a vehicle 100 according to an embodiment of theinvention from different perspective views. In FIGS. 1-3, the vehicle100 has a jet augmenting propulsive system with particular emphasis onVTOL capabilities. More specifically, vehicle 100 includes a main body101 having a fore portion 102 and a tail portion 103. Main body 101 mayinclude a cockpit portion (not shown) configured to enable mannedoperation of the vehicle 100. As with all flying/sailing craft, vehicle100 has a starboard side and a port side. A fluid generator 104 iscoupled to the main body 101 and produces a fluid stream. In anembodiment, the fluid generator 104 is disposed in the main body 101. Atleast one fore conduit (111 in FIG. 3) and at least one tail conduit 112are fluidly coupled to the generator 104.

First and second fore ejectors 105, 106 are fluidly coupled to the atleast one fore conduit 111, coupled to the fore portion 102 andrespectively coupled to the starboard side and port side. The foreejectors 105, 106 respectively include outlet structure 107, 108 out ofwhich fluid from the at least one fore conduit 111 flows at apredetermined adjustable velocity. Additionally, the entirety of each ofthe fore ejectors 105, 106 is rotatable about an axis oriented parallelto the leading edges of the fore ejectors (i.e., transverse axis) toprovide thrust orientation with both forward and upward components, forexample, allowing the vehicle 100 to take off and continue climbing atmuch steeper angles of attack and hence reducing the runway lengthneeded. At the end of the climb or during the climb, the fore ejectors105, 106 can be realigned to the main direction of flight or shut offcompletely by turning off the bleed valves of the engine/gas generator104 and adapting the speed and operation of the gas generatoraccordingly, driving the rear propulsion system (e.g., tail ejectors109, 110). After landing, the fore ejectors 105, 106 can be swiveled 180degrees to provide a thrust reverse against the direction of thelanding, shortening the landing length. In an embodiment, the entiretyof each of the fore ejectors 105, 106 is rotatable about an axisoriented perpendicular to the leading edges of the fore ejectors.

First and second tail ejectors 109, 110 is fluidly coupled to the atleast one tail conduit 112 and coupled to the tail portion 103. The tailejectors 109, 110 include outlet structure 113, 114 out of which fluidfrom the at least one tail conduit 112 flows at a predeterminedadjustable velocity. Additionally, the entirety of each of the tailejectors 109, 110 is rotatable about an axis oriented parallel to theleading edges of the tail ejectors (i.e., transverse axis). In anembodiment, the entirety of each of the tail ejectors 109, 110 isrotatable about an axis oriented perpendicular to the leading edges ofthe tail ejectors.

In an embodiment, the fluid generator 104 includes a first region inwhich the fluid stream is at a low temperature and a second region inwhich the fluid stream is at a high temperature. The at least one foreconduit 111 provides fluid from the first region to the fore ejectors105, 106, and the at least one tail conduit 112 provides fluid from thesecond region to the tail ejectors 109, 110.

A primary airfoil element 115 is coupled to the tail portion 103.Element 115 is located directly downstream of the fore ejectors 105, 106such that the fluid from the fore ejectors flows over at least oneaerodynamic surface of the primary airfoil element. In an embodiment,the primary airfoil element 115 is a closed wing having a leading edge121 and a trailing edge 122, the leading and trailing edges of theclosed wing defining an interior region 123. Tail ejectors 109, 110 areat least partially disposed within the interior region 123 (i.e.,between leading edge 121 and trailing edge 122) and are controllablymovable (e.g., advancement, retraction, etc.) within the interior regionrelative to the airfoil element 115. As such, a shroud is formed byprimary airfoil element 115 around the tail ejectors 109, 110, therebyforming a macro-ejector.

The vehicle 100 further includes first and second canard wings 117, 118coupled to the fore portion 102 and respectively coupled to thestarboard side and port side. The canard wings 117, 118 are configuredto develop boundary layers of ambient air flowing over the canard wingswhen the vehicle 100 is in motion. The canard wings 117, 118 arerespectively located directly upstream of the fore ejectors 105, 106such that the fore ejectors are fluidly coupled to the boundary layers.The fore ejectors 105, 106 respectively include inlet portions (i.e.,leading edges) 119, 120, and the fore ejectors are positioned such thatthe boundary layers are ingested by the inlet portions.

FIG. 4 illustrates in exploded view a vehicle 400 according to analternative embodiment. For the sake of brevity, elements illustrated inFIG. 4 having characteristics identical to their counterpartsillustrated in FIGS. 1-3 are denoted using the same reference numeral.Vehicle 400 includes a fluid generator 104, tail ejectors 109, 110, atail conduit 112 to guide hot pressurized exhaust gas to the tailejectors, and a rear thruster support strut 401. Vehicle 400 furtherincludes canard wings 117, 118, a bleed air manifold 402 and a foreconduit 111 linking the bleed air manifold to a control valve box 403having a motor control valve 404 that modulates both fluid flow to foreejectors 105, 106 and balance of the primary flow supply between thefore ejectors. Flexible lines 405 guide compressed bleed air fromcontrol valve box 403 to fore ejectors 105, 106. Each of fore ejectors105, 106 includes a flange 406 and a motor 407 for swiveling the foreejectors about shaft 408.

Vehicle 400 further includes primary airfoil element 115 with controlsurfaces such as rudders, elevons, elevators, etc., an additionalclosed-wing airfoil element 409, and a secondary closed-wing airfoilelement 410. The secondary airfoil element 410 has a leading edgelocated directly downstream of the outlet structure 113, 114 of tailejectors 109, 110 such that the fluid from the tail ejectors flow over asurface of the at least one secondary airfoil element. Vehicle 400further includes a central fin and rudder 124, tail portion 103 carryingtank, fluid generator 104, and controls, and fore portion 102.

FIG. 5 illustrates a vehicle 500 according to an alternative embodiment.For the sake of brevity, elements illustrated in FIG. 5 havingcharacteristics identical to their counterparts illustrated in FIGS. 1-3are denoted using the same reference numeral. Vehicle 500 includes aturbo-propeller propulsive system with particular emphasis on shorttake-off and landing (STOL) capabilities. Vehicle 500 includes all ofthe features of vehicle 100 except for tail ejectors 109, 110. Instead,vehicle 500 includes a propeller 510 driven by a turbine (not shown),which is in turn powered by fluid generator 104. An embodiment caninclude a support assembly 520, such as legs or other appropriatedevice, that provide support to vehicle 500 such that there is enoughspace and/or offset between the propeller 510 and a landing/takeoffsurface when the vehicle 500 is at rest. Support assembly 520 preferablyextends from the tail portion 103 and is substantially parallel to themain body 101.

FIGS. 6A-6D illustrate the progression from take-off to level flightrelative to a landing/takeoff surface 600 of vehicle 100. The moveablefore ejectors 105, 106 may be responsible for the fine tuning of thevehicle 100 attitude in-flight up to level flight (cruise). One aspectof this embodiment is that the tail ejectors 109, 110, being larger andemploying hot gases as primary fluid, do not necessarily need to swivelto control the attitude, while the fore ejectors 105, 106, being smallerand operating with colder gas from the compressor discharge or bleeds,can be swiveled to maintain the altitude and attitude of the vehicle 100and drive its orientation in flight to the desired position andattitude. The fore ejectors 105, 106 could then be shut down from acentral control valve that closes the bleed port, and/or retractedinside the fore portion 102, allowing the fluid generator 104 to operateat throttle pulled condition (less than 100% speed) and still generatehot gases in the back to supply the tail ejectors 109, 110 with primaryfluid, bleed valve closed. An augmentation of 2:1 is still possible inlevel flight, with minor or no contribution from the boxed wing actingas shroud for the larger or macro-ejector formed by the tail ejectors109, 110 and airfoil element 115 itself.

The advantageous effect of combining the tail ejectors 109, 110, whichproduce high-speed airflow, with the primary airfoil element 115 togenerate additional thrust augmentation is particularly useful whentaking-off in a tailsitter configuration. The tail ejectors 109, 110become the primary nozzle of a classical ejector. Then the primaryairfoil element 115, together with the tail ejectors 109, 110 to form amacro-ejector, generates a thrust augmentation of roughly 1.1-1.2compared to simple thrusters without the shroud. The tail ejectors 109,110 themselves can also produce a thrust augmentation of above 2,perhaps close to 3:1. As such, instead of obtaining a unit of thrust bysimply using two turbojets, a total thrust augmentation of minimum2*1.1=2.2 and up to a maximum of 3*1.2=3.6 augmentation factor isobtained, allowing the take-off of a heavier vehicle. As it levels offto cruise conditions, the engines can be throttled back, and theaugmentation also decreases to match and overcome drag and propel thevehicle forward in level flight.

FIG. 7 illustrates the upper half a turboshaft/turboprop engine withhighlights of the stations of the flow. The bottom half contains thesame engine stripped of the shaft and turbine driving the shaft (freeturbine driving the propeller, in this case) and using the gas generatorto drive a jet augmenting system of the preferred embodiment of thepresent invention. FIG. 7 shows the changes that would be optionallyadvantageous for transforming a turboshaft designed engine into a gasgenerator for the jet augmenting system and highlights theinterchangeability of the disclosed system.

In FIG. 7, a puller propeller configuration is shown in the upper half.In contrast, one embodiment of the present invention has the shaftpointing to the right, where the pusher propeller is located. The tophalf contains a compressor, a combustor and two turbines, one connectedto the compressor and one connected to the propeller via a shaft.Station 2 represents a compressor inlet; a compressor outlet station 3;a combustor inlet 31; a combustor outlet 4; a first turbine (connectedto and driving the compressor) inlet 41; a first turbine outlet 44; aninlet 45 to the free turbine; an exit 5 from the free turbine, an outlet6 from the turbine and exhaust; and exhaust (from the overall system) 8.The bleed system from station 3 is used in this embodiment as motivefluid for the front thrusters of the system. The remainder of theworking fluid is used by the gas generator to drive the free turbine,which is extracting power to drive the propeller. In the lower half, thesystem is stripped off the free turbine and the shaft (and implicitlythe propeller), but all the other elements remain the same. The systemis similar, with the first turbine driving the compressor, except thefree turbine is eliminated, allowing the system to become a gasgenerator that produces at the station 44 a pressure a total pressure of202.514 kiloPascals at a total temperature of 1248.65 Kelvin. Thisenergy carrying flow can now be used as motive fluid for the tailejectors 109, 110 of the jet augmenting system of the preferredembodiment of the present invention.

Other gas generators can be designed to produce, at normal operatingconditions, a pressure ratio of around 2. An embodiment of the presentinvention can result in augmentation ratios exceeding 1.5 and variousdesigns of the thrusters can reach up to and including 2.75:1augmentation ratio. As such, a jet augmenting system of this embodimentoperating in these conditions can increase the thrust by 1.4-3 times.Conversely, the specific fuel consumption is reduced as the same amountof fuel is used to produce the conditions at station 44, and 1.4 timesmore thrust is obtained from the exhaust gas at that condition, used asmotive fluid in the rear and front thrusters. When compared to the fuelconsumption of conventional small turbojets, typically at 1.5 lb/hr perlbf, the specific fuel consumption with the disclosed jet augmentingsystem is lowered by 1.4 times, to around 1.07 lb/hr fuel per each lbfproduced. One or more embodiments show a reduction of up to 2.0 timescompared to the original 1.5 lb/hr of fuel per lbf produced, bringingthe system to a highly performant 0.75 lb/hr fuel per each lbf thrustproduced, without the use of a free turbine.

An embodiment of the present invention includes two rear gas generators;a first rear large, moveable thruster; a second rear, large, moveablethruster; transition piece to guide hot pressurized exhaust gas to rearthrusters from each rear gas generator; support thrusters; manifold,compressor bleed air; pipe linking bleeds manifold to control valve box;control valve that modulates both flow to front thrusters as additionalmotive fluid and balance between front thrusters primary flow supply;motor control valve; flexible line guiding compressed bleed air fromcontrol valve box to front thrusters; front thruster main body; frontthruster flange; motor for swiveling the front thruster; shaft; endpanel/winglet canard wing; front moveable canard; a first design boxwing and control surfaces (rudder, elevons, elevator); a second designbox wing; a design sweptback box wing; central fin and rudder; main boxof fuselage carrying tank, gas generator, controls; and front fuselage;and front gas generators for the front thrusters.

FIGS. 8-11 illustrate different perspective views of one embodiment ofthe invention having a jet-augmenting propulsive system with particularemphasis on VTOL capabilities. FIGS. 12-14 illustrate differentperspective views of another embodiment including control airfoils. InFIGS. 15 and 16, the flying vehicle is illustrated in a position oftransition from vertical takeoff to cruise condition.

An embodiment of the present invention addresses the first issue ofthrust-to-weight ratio and sizing of the engine through enhancing andaugmenting the thrust and using several gas generators distributedthroughout the flying vehicle. In a preferred embodiment of the presentinvention, the thrusters themselves are designed to allow foraugmentation exceeding 2:1 and close to 3:1. This means that thesethrusters are designed to produce a thrust that is 2-3 times greaterthan the thrust produced by a conventional turbojet. Thrust augmentationdesigns are disclosed in the '389 Application.

In a preferred embodiment of the present invention, the thruster is usedwith a gas generator as a source for primary flows. FIGS. 8-11illustrate a vehicle 5 according to an embodiment of the invention fromdifferent perspective views. In FIGS. 8-11, the vehicle 5 has a jetaugmenting propulsive system with particular emphasis on VTOLcapabilities. More specifically, vehicle 5 includes a main body 55having a fore portion 60 and a tail portion 65. Main body 55 may includea cockpit portion 35 configured to enable manned operation of thevehicle 5. As with all flying/sailing craft, vehicle 5 has a starboardside and a port side. Fluid generators 45 a, 45 b are coupled to themain body 55 and produce fluid streams. In an embodiment, the fluidgenerators 45 a, 45 b are disposed in the main body 55. Tail conduits 70a, 70 b are fluidly coupled to the generators 45 a, 45 b.

Fore fluid generators 25 a, 25 b are coupled to the main body 55 towardthe fore portion 60. First and second fore ejectors 20 a, 20 b arefluidly coupled to the fore fluid generators 25 a, 25 b by first andsecond fore conduits 75 a, 75 b, coupled to the fore portion 60 andrespectively coupled to the starboard side and port side. The foreejectors 20 a, 20 b respectively include outlet structure (not shown,but similar to outlet structures 107, 108 illustrated in FIG. 1) out ofwhich fluid from the fore fluid generators 25 a, 25 b flows at apredetermined adjustable velocity. Additionally, the entirety of each ofthe fore ejectors 20 a, 20 b is rotatable about an axis orientedparallel to the leading edges of the fore ejectors (i.e., transverseaxis) to provide thrust orientation with both forward and upwardcomponents, for example, allowing the vehicle 5 to take off and continueclimbing at much steeper angles of attack and hence reducing the runwaylength needed.

At the end of the climb or during the climb, the fore ejectors 20 a, 20b can be realigned to the main direction of flight or shut offcompletely by turning off the fore fluid generators 25 a, 25 b,retracting the fore ejectors into the main body 55, and adapting thespeed and operation of the gas generator accordingly, driving the rearpropulsion system (e.g., tail ejectors 10 a, 10 b). At landing, the foreejectors 20 a, 20 b can be swiveled 180 degrees to provide a thrustreverse against the direction of the landing, shortening the landinglength. In an embodiment, the entirety of each of the fore ejectors 20a, 20 b is rotatable about an axis oriented perpendicular to the leadingedges of the fore ejectors.

First and second tail ejectors 10 a, 10 b are fluidly coupled to thetail conduits 70 a, 70 b and coupled to the tail portion 65. The tailejectors 10 a, 10 b include outlet structure (not shown, but similar tooutlet structures 113, 114 illustrated in FIG. 1) out of which fluidfrom the tail conduits 70 a, 70 b flows at a predetermined adjustablevelocity. Additionally, the entirety of each of the tail ejectors 10 a,10 b is rotatable about an axis oriented parallel to the leading edgesof the tail ejectors (i.e., transverse axis). In an embodiment, theentirety of each of the tail ejectors 10 a, 10 b is rotatable about anaxis oriented perpendicular to the leading edges of the tail ejectors.

A primary airfoil element 15 is coupled to the tail portion 65. Element15 is located directly downstream of the fore ejectors 20 a, 20 b suchthat the fluid from the fore ejectors flows over at least oneaerodynamic surface of the primary airfoil element. In an embodiment,the primary airfoil element 15 is a closed wing having (similar toelements 121, 122 and 123 illustrated in and discussed with reference toFIG. 1) a leading edge and a trailing edge, the leading and trailingedges of the closed wing defining an interior region. Tail ejectors 10a, 10 b are at least partially disposed within the interior region(i.e., between the leading edge and trailing edge) and are controllablymovable (e.g., advancement, retraction, etc.) within the interior regionrelative to the airfoil element 15. As such, a shroud is formed byprimary airfoil element 15 around the tail ejectors 10 a, 10 b, therebyforming a macro-ejector.

The vehicle 100 further includes first and second canard wings 30 a, 30b coupled to the fore portion 60 and respectively coupled to thestarboard side and port side. The canard wings 30 a, 30 b are configuredto develop boundary layers of ambient air flowing over the canard wingswhen the vehicle 5 is in motion. The canard wings 30 a, 30 b arerespectively located directly upstream of the fore ejectors 20 a, 20 bsuch that the fore ejectors are fluidly coupled to the boundary layers.The fore ejectors 20 a, 20 b respectively include inlet portions (i.e.,similar to inlet portions 119, 120 illustrated in and discussed withreference to FIG. 1), and the fore ejectors are positioned such that theboundary layers are ingested by the inlet portions. The first and secondcanard wings 30 a, 30 b each have a leading edge, and the entirety ofeach of the first and second canard wings is rotatable about an axisoriented parallel to the leading edge.

During level flight, further augmentation can be achieved through asecondary, major ejector that can be formed by using the exhaust fromthe thrusters 10 a, 10 b in conjunction with, for example, the boxedwing 15 of the vehicle 5 acting as a shroud. The wings may also take anyother shape that is designed in such a way to allow the high-speedexhaust of the thrusters 10 a, 10 b to serve as primary nozzle for theejector formed by the wing 15 (“shroud”) and thrusters. The effects ofthe shroud can further augment the thrust by at least 10-25%. In effect,the thrusters 10 a, 10 b and the shroud can have a combined effect ofthrust augmentation of, for example, 1.1 (from shrouded thrusters) times2.5 (from Thrusters) augmentation, which results in a total augmentationof 2.75. Therefore, one skilled in the art would appreciate that such asystem would produce a thrust that defeats the drag of the vehiclemoving at speed, by augmenting an otherwise ˜2.75 thrust generated by asimple turbojet.

The thrusters 10 a, 10 b combined with the box wing 15 generateadditional thrust augmentation. This effect is particularly useful whentaking-off. The thrusters 10 a, 10 b become the primary nozzle of aclassical ejector. Then the shroud (together with the thrusters 10 a, 10b to form a macro-ejector) generates a thrust augmentation of roughly1.1-1.2 compared to the simple thrusters without the shroud. Thethrusters 10 themselves can also produce a thrust augmentation of above2, close to 3:1 if thrusters according to an embodiment are used. Assuch, instead of obtaining a unit of thrust by simply using the twoturbojets, a total thrust augmentation of minimum 2*1.1=2.2 and up to amaximum of 3*1.2=3.6 augmentation factor is obtained, allowing thetake-off of a heavier vehicle. As it levels off to cruise conditions,the engines are throttled back, and the augmentation also decreases tomatch and overcome drag and propel the vehicle 5 forward in levelflight.

In any aircraft which takes off vertically, the aircraft would naturallyneed to adjust its attitude to level off at the acceptable attitude andreduce its thrust in order to keep the aircraft flying forward at aconstant cruise speed. Thrust reduction via throttle reduction mayadjust the power needed to overcome the drag of the aircraft only, whichmay also mean a lesser augmentation of the entire system and sufficientto propel the aircraft forward and maintain its speed.

In one embodiment of the present invention, a 1500-lbs aircraft mayemploy two 300-lbf turbojets adapted to become a gas generator in therear of the aircraft (Rear Gas Generators) and another two 150 lbf classturbojets adapted to become a gas generator in the nose of the aircraft(Forward Gas Generators). In this embodiment, these thrust augmentingejectors can produce an augmentation of, for example, 1.75 times theoriginal, which means 300 multiplied by 1.75, which results in 525 lbfaugmented thrust for each thruster, therefore a total of 1050 lbf in therear of the aircraft. The thrusters 10 may be swiveled to pointdownwards by rotation of the thrusters or by rotation of the entire gasgenerator and thruster assembly. As the flying vehicle 5 gains altitude,the thrusters 10 or entire assembly gas generator-thrusters rotate inthe forward moving, level flight position, with the thrusters' hot gasesoriented through the box wing 15 forming a shroud, at final level flightposition. With a wing such as a boxed structure around the mainthrusters 10 a, 10 b to shroud these thrusters in level flight, theoverall augmentation of the thrust becomes, for example, e.g., 1.15multiplied by 525 lbf, resulting in 603.75 lbf, and hence rapidlyaccelerating the vehicle forward.

The forward generators 25 a, 25 b would similarly augment the thrust toobtain ˜525 lbf combined in the forward area of the aircraft 5,balancing the vehicle and providing a safe takeoff and landing attitude.Once the vehicle 5 is at safe altitude and forward speed, the forwardgenerators 25 a, 25 b may be shut down and their associated forwardthrusters 20 may be retracted inside the fuselage to reduce drag. Theforward thrusters 20 may be extended again when close to landing ortransitioning to hover, concomitantly with the forward gas generatorrestart. It should be noted that thrusters 10, 20 can include or consistof turbojets and/or turbopropellers.

As the fuel is consumed on board the vehicle 5, the weight of thevehicle becomes lighter and the acceleration of the vehicle becomeslarger, hence increasing speed and acceleration. Because the vehicle 5is inhabited, the accelerations need not exceed the currenthuman-limited accelerations that are restricted for human safety andnon-life-threatening standards. As such, after a short time, the vehicle5 may have the ability to change its attitude and achieve level flightby throttle and control surface changes. Lift increases as the vehicle 5changes its attitude, while the combined augmentation also diminishes invalue due to the throttle pull back. The vehicle 5 may then achievelevel flight by concomitantly reducing the engine load (ergo gasgenerator primary stream) to the thrusters 10 in the first level andallowing the boxed wing 15 to produce the lift necessary to maintain theattitude, while the thrusters only produce enough thrust to overcomedrag.

Conversely, on approach to the destination, the attitude of the aircraft5 can be adjusted with an increased angle of attack and the thrustaugmentation again displaces the need for lift, as the forward speedreduces and the aircraft eventually can land vertically, on its tail,balanced by the thrusters 10, 20 and its combined augmentation effect.

One or more embodiments of the present invention are able to overcomethe second issue of balancing the forces and moments by having smallermoment arms that are needed to balance them around the center of mass,which is achieved by having a distribution of thrust across variouslocations in the aircraft. This, in turn, allows these embodiments tohave more control and makes it easier to maintain a hover/uprightposition.

As discussed in the '389 and '407 Applications, the unique technologyallows for the distribution of thrust across various locations of theaircraft, with augmentation levels achieved in various thrusters (e.g.,in front, thrusters 20 behind the canard wings (movable canards) 30 a,30 b, employed only at hovering phases take-off and landing and turnedoff at level flight and in the back, the “hot thrusters” 10 thatgenerate the bulk of the thrust).

In the embodiment of a 1500 # heavy vehicle 5 of FIG. 8, two smallerforward generators 25 a, 25 b are placed in the nose of the vehicle eachfeeding a smaller thruster 10 a, 10 b. The role of these forwardgenerators 25 a, 25 b and thrusters 20 a, 20 b, which are placed nearthe canards 30, is to assist the take off by balancing the moments andforces in conjunction with the rear, larger thrusters, 10 and attain thelevel flight condition for which sufficient lift force is generated bythe aerodynamic features of the vehicle 5 and complemented by the rearthrusters system.

At the point where the lift generated by the vehicle 5 becomessufficient, the forward generators 25 a, 25 b and thrusters 20 shut offand retract within the fuselage, reducing the drag and allowing highspeed of the vehicle when only the rear thrusters 10 operate.

In one embodiment a 1500 # Flying Vehicle uses a combined 500 #augmenting thrusters 20 in the nose, supplied with gas by two forwardgenerators 25 a, 25 b modified from 150 lbf turbojets. An augmentationof 1.75 yields a thrust of 262.5 lbf for each of the systems, for acombined nose thrust of 525 lbf. These forward generators 25 a, 25 b aregradually throttled back and eventually shut off when the vehicle 5 hasreached the speed at which the aerodynamic lift force is sufficient, thethrusters 10 a, 10 b have completely swiveled into cruise position andproduce a thrust enough to overcome drag.

On approach and landing, the front thrusters 20 are once again startedwith some assist from hot bleed air off the generators' 45 a, 45 bcompressor discharge ports, to complement the lift reduction and allowthe vehicle 5 to be controlled, while the rear thrusters 10 re-orient inlanding/take off position.

A conventional small (<1500 lbf thrust) mini jet engine usually providesthrust at a single location, typically at the center of the exhaustsection. Some small turbofans also provide the thrust in a concentratedpoint on the aircraft. One or more embodiments of the present inventionallow the distribution of the thrust in a nearly linear and/ornon-circular manner, as opposed to a circular manner as is the case inthe existing prior art, and thus distribute the thrust per the length ofa wing or other airfoils and/or control surfaces of an aircraft. In thevehicle 5, all gas generator and compressor bleed air streams may beused as motive fluids for the augmenting thrusters. Because thisembodiment allows the distribution of the thrust in a linear, mainlynon-circular and distributed, not at a concentrated point, it achievesbetter propulsive efficiency of the aircraft. In addition, there is theoptionally advantageous feature of molding and shaping the thrusteraccording to the shape of the airfoils to obtain better performance(e.g., increasing the stall margin of a given canard wing if thruster isplaced downstream of it, or augmenting the lift on a main wing if thethruster is placed at an optimal location upstream of said main wing).The distributed thrust improves the performance of the aircraft bydistributing an otherwise e.g. 600 lbf turbojet hot and fast stream froma concentrated location at the back of the turbojet engine in, forexample, at least four locations on the aircraft. In addition, it wouldallow VTOL or STOL. In this example, thrusters are mounted at these fourlocations on the vehicle in an optimal manner, such that they are (i)receiving the pressurized air or gas stream from the compressor bleedsystem and exhaust of the gas generator respectively or a combinationthereof and (ii) augmenting each of the four thrust forces that wouldotherwise result from the simple isentropic expansion of the fourprimary streams by 1.5-3 times. This also results in an advantageousdistributed flow and thrust from the four locations, thus enhancing theaircraft maneuverability and propulsive efficiency.

FIGS. 15-16 illustrate the progression from take-off to level cruiseflight of a vehicle 5 that has moveable rear thruster(s) 10 on thetail-end and retractable nose thruster(s) 20 on the front-end, with thenose thruster(s) being responsible for the fine tuning of the aircraftattitude in flight up to level flight (cruise). One of the advantages ofthis embodiment is that the nose thrusters 20, being smaller andemploying hot gases from the forward generators 25 a, 25 b as primaryfluid, do not necessarily need to swivel a lot or even at all to controlthe attitude if control surfaces are placed in position downstream ofthem, while the rear thrusters 10, being larger and operating withexhaust gas from the generators 45 a, 45 b, can be swiveled to maintainthe altitude and attitude of the aircraft and drive its orientation inflight to the desired position and attitude. The nose thrusters 20 couldthen be shut down by shutting off the forward generators 25 a, 25 b,and/or retracted inside the fuselage, allowing the vehicle to fly onlyon the rear engines operating at throttle pulled condition (less than100% speed) and still generate hot gases to supply the hot thrusters 10with primary fluid. An augmentation of 2:1 is still possible in levelflight, with minor or no contribution from the boxed wing 15 acting asshroud for the larger or macro-ejector formed by the hot thruster(s) andwing itself.

An embodiment includes a turboprop STOL version of the presentinvention. The turboprop version of the augmented propulsion systemconsists of the same front system of augmentation of thrust based onmotive fluid provided by the two nose gas generators. The bleed systemof the generators 45 a, 45 b may also be employed in furtheraugmentation of the front thrusters, by providing the port and starboardfront thrusters 20 a, 20 b with additional motive air from the bleed ofthe rear gas generators' compressors. The front thrusters provide anaugmentation corresponding to specific thrust of 100-300 lbf for eachlb/sec of motive air of exhaust gas provided by the bleed system andfront gas generators exhaust. This value exceeds by far the typical50-65 lbf/lb/sec specific thrust obtained with small turbojet engines,due to limited efficiencies of the components and lack of advancedtechnologies. When turned into a gas generator, the value of thecompressed air and exhaust gas combined is utilized by employing thethrusters in front and back of the system resulting in augmentationratios of over 2:1. As such, more thrust can be obtained from the sameenergy input.

In an embodiment, a control valve is employed to provide the balance offlow between the port and starboard thrusters 10 a, 10 b. The modulationof the air can be obtained with valves placed between the engine bleedand the control valve box 80. The valves allow for control of the flowon each thruster and/or balance of the flow of the motive air betweenthe two front thrusters by opening or closing a passage to one or bothof the front thrusters and changing the motive fluid supply. This, inturn, generates an imbalance in thrust, and the imbalance results in thechange in the aircraft attitude. The thrusters can also be swiveledaround their main axis, while being modulated for primary flow (motivefluid flow) at the same time. This allows for control on the pitch androll as well as some limited control on the yaw, and combinationsthereof.

An embodiment includes a jet augmenting propulsive system STOL versionof the present invention. In this embodiment, the vehicle rearpropulsion system consists of a jet augmenting system. Turbojets supplya high-speed exhaust gas through the box wing of the aircraft, producein effect an augmentation of at least 1.05 and up to 1.15 times theiroriginal thrust. Turbojets are delivering in effect the motive gas toaugment the thrust in a macro-ejector whose shroud is the box wingitself. The jet augmenting system is specifically designed to allow fastmovement of the vehicle at the cost of additional fuel consumption,resulting in airspeeds of the vehicle exceeding 200 MPH and propulsiveefficiencies exceeding 75%. The system results in a typical specificfuel consumption of 1.3-1.4 lb/hr of fuel per lbf generated, which ismore economical than the 1.5 typical rate of the small turbojets. Theselevels are much more performant than the typical 1.5 lb/hr per lbfusually obtained with small turbojets, the majority of current marketsfor drones. The system can also achieve the performance of specific fuelconsumption of a low-bypass turbofan at much smaller scale and withoutemploying a free turbine and a fan, per se, reducing thus the weight andcomplexity of the entire propulsion system and eliminating a large,moving assembly such as the fan/free turbine assembly.

Alternatively or in addition to, if the mission of the aircraft islonger duration/range and slower airspeeds at higher propulsiveefficiencies, then the rear section of the propulsive system can be madeflexible enough to be replaced by a turbine/propeller system whilekeeping the common, identical gas generator (front of the propulsivesystem) and augmenting thrusters. The turbine will receive the same flowas in the case of the jet augmenting system, but will extract the energyfrom the gas generator exhaust flow and turn it into mechanical workused to rotate the propeller rather than fluidically augment the flow inan ejector type thruster. The interfaces are very similar, thereplacement consisting of the removal of the transition piece conduitwith a conduit that guides the hot, pressurized gases towards the freeturbine driving the propeller, after which the exhaust gases areexpelled in the downstream direction and into the wash of the propeller.The advantage of such a flexible system is that with the similararrangement, a turbopropeller pusher or a jet augmenting system can beinterchangeable, allowing the customer to choose the system based on themission at hand. As such, a turbopropeller pusher system as describedcan achieve a specific fuel consumption level of below 0.6 lb/h per eachhorsepower or equivalent thrust lbf achieved. In one embodiment of thepresent invention, the flying vehicle may be able to transport a singleperson as far as 200 miles away moving at an average cruise speed of 150mph.

Furthermore, the propeller can be perfectly contained by, for example,the box wing system described elsewhere, and thus the noise generated bythe turboprop can be significantly reduced by direct (box wing) andindirect means (noise abatement materials inside the wing). In addition,the turboprop still benefits from the presence of the front thrustersand the use of bleed air to power them, allowing not only VTOL but,where appropriate and VTOL not necessary, short take-off and landing.

In one or more embodiments of the present invention, the short take-offand landing (STOL) concept can be achieved by the employment of thefront thrusters, significantly lowering the runway length required fortake-off. By swiveling the thrusters, additional vectored thrust can beoriented to increase pitch during take-off and reduce the length neededas compared to a conventional aircraft. The front thrusters may be shutoff during cruise or loitering, or re-activated at various stages of theflight, to augment lift, or thrust or both. The augmentation of thethrust can be accomplished through the very design of the thrusters. Theaugmentation of the lift can be accomplished by the placement of thefront thrusters in relation to both the canard (front wings) and themain box wing. The downstream location of the front wing delays stall ofthe front wings, allowing operation at higher angles of attack andhigher lift coefficients before stall occurs. This is due to the lowerpressure created in front of the thrusters, delaying the separation onthe top of the wing, the main cause of stall on most wings at highangles of attack. The lift augmentation due to the main wing is mainlydue to the increased flow resulting from the front thrusters, locallyhigher than the airspeed of the vehicle, which said flow is guided overthe bottom part of the box wing and, as known to those familiar with thematter, augmenting the lift of the main wing.

The same principles can be applied to a STOL embodiment. In anembodiment, a port front thruster is swiveled at an angle favoring thethrust orientation with both forward and upward components, allowing thevehicle to take off and continue climbing at much steeper angles ofattack and hence reducing the runway length needed. At the end of theclimb or during the climb, the front thruster can be realigned to themain direction of flight or shut off completely by turning off the bleedvalves of the engine/gas generator and adapting the speed and operationof the gas generator accordingly, driving the rear propulsion systemonly (e.g., jet augmenting system or turbopropeller). After landing, thefront thrusters can be swiveled 180 degrees to provide a thrust reverseagainst the direction of the landing, shortening the landing length.

In an embodiment, and referring to FIGS. 12-14, a vehicle 1200 has a jetaugmenting propulsive system with particular emphasis on VTOLcapabilities. More specifically, vehicle 1200 includes a main bodysimilar to main body 55 having a fore portion and a tail portion. Mainbody may include a cockpit portion 1208 configured to enable mannedoperation of the vehicle 1200. As with all flying/sailing craft, vehicle1200 has a starboard side and a port side. At least one fluid generator1211 is coupled to the main body and produces a fluid stream. In anembodiment, the fluid generator 1211 is disposed in the main body. Atleast one fore conduit and at least one tail conduit are fluidly coupledto the generator 1211.

First and second fore ejectors 1201, 1202 are fluidly coupled to the atleast one fore conduit, coupled to the fore portion and respectivelycoupled to the starboard side and port side. The fore ejectors 1201,1202 respectively include outlet structure out of which fluid from theat least one fore conduit flows at a predetermined adjustable velocity.Additionally, the entirety of each of the fore ejectors 1201, 1202 isrotatable about an axis oriented parallel to the leading edges of thefore ejectors (i.e., transverse axis) to provide thrust orientation withboth forward and upward components, for example, allowing the vehicle1200 to take off and continue climbing at much steeper angles of attackand hence reducing the runway length needed. At the end of the climb orduring the climb, the fore ejectors 1201, 1202 can be realigned to themain direction of flight or shut off completely by turning off the bleedvalves of the engine/fluid generator 1211, retracting the fore ejectorsinto the main body, and adapting the speed and operation of the gasgenerator accordingly, driving the rear propulsion system (e.g., tailejectors 1203, 1204). At landing, the fore ejectors 1201, 1202 can beswiveled 180 degrees to provide a thrust reverse against the directionof the landing, shortening the landing length. In an embodiment, theentirety of each of the fore ejectors 1201, 1202 is rotatable about anaxis oriented perpendicular to the leading edges of the fore ejectors.

First and second tail ejectors 1203, 1204 are fluidly coupled to atleast one tail conduit and coupled to the tail portion. The tailejectors 1203, 1204 include outlet structure out of which fluid from theat least one tail conduit flows at a predetermined adjustable velocity.Additionally, the entirety of each of the tail ejectors 1203, 1204 isrotatable about an axis oriented parallel to the leading edges of thetail ejectors (i.e., transverse axis). In an embodiment, the entirety ofeach of the tail ejectors 1203, 1204 is rotatable about an axis orientedperpendicular to the leading edges of the tail ejectors.

In an embodiment, the fluid generator 1211 includes a first region inwhich the fluid stream is at a low temperature and a second region inwhich the fluid stream is at a high temperature. The at least one foreconduit provides fluid from the first region to the fore ejectors 1201,1202, and the at least one tail conduit provides fluid from the secondregion to the tail ejectors 1203, 1204.

A primary airfoil element 1215 is coupled to the tail portion. Element1215 is located directly downstream of the fore ejectors 1201, 1202 suchthat the fluid from the fore ejectors flows over at least oneaerodynamic surface of the primary airfoil element. In an embodiment,the primary airfoil element 1215 is a closed wing having a leading edgeand a trailing edge, the leading and trailing edges of the closed wingdefining an interior region. Tail ejectors 1203, 1204 are at leastpartially disposed within the interior region (i.e., between leadingedge and trailing edge) and are controllably movable (e.g., advancement,retraction, etc.) within the interior region relative to the airfoilelement 1215. As such, a shroud is formed by primary airfoil element1215 around the tail ejectors 1203, 1204, thereby forming amacro-ejector.

The vehicle 1200 further includes first and second canard wings 1209,1210 coupled to the fore portion and respectively coupled to thestarboard side and port side. The canard wings 1209, 1210 are configuredto develop boundary layers of ambient air flowing over the canard wingswhen the vehicle 1200 is in motion. The canard wings 1209, 1210 arerespectively located directly upstream of the fore ejectors 1201, 1202such that the fore ejectors are fluidly coupled to the boundary layers.The fore ejectors 1201, 1202 respectively include inlet portions (i.e.,leading edges), and the fore ejectors are positioned such that theboundary layers are ingested by the inlet portions. Vehicle 1200 mayfurther include control airfoils 1205, 1206, 1207.

Although the foregoing text sets forth a detailed description ofnumerous different embodiments, it should be understood that the scopeof protection is defined by the words of the claims to follow. Thedetailed description is to be construed as exemplary only and does notdescribe every possible embodiment because describing every possibleembodiment would be impractical, if not impossible. Numerous alternativeembodiments could be implemented, using either current technology ortechnology developed after the filing date of this patent, which wouldstill fall within the scope of the claims.

Thus, many modifications and variations may be made in the techniquesand structures described and illustrated herein without departing fromthe spirit and scope of the present claims. Accordingly, it should beunderstood that the methods and apparatus described herein areillustrative only and are not limiting upon the scope of the claims.

What is claimed is:
 1. A vehicle, comprising: a main body having a foreportion, a tail portion, a starboard side, a port side and a cockpitformed therein to accommodate a human pilot; a first fluid generatorcoupled to the main body and producing a first fluid stream; at leastone tail conduit fluidly coupled to the first generator; first andsecond fore ejectors coupled to the fore portion and respectivelycoupled to the starboard side and port side, the fore ejectorsrespectively comprising an outlet structure out of which fluid flows ata predetermined adjustable velocity; at least one tail ejector fluidlycoupled to the at least one tail conduit and coupled to the tailportion, the at least one tail ejector comprising an outlet structureout of which fluid from the at least one tail conduit flows at apredetermined adjustable velocity; a primary airfoil element coupled tothe tail portion and comprising a closed wing having a leading edge anda trailing edge, the leading and trailing edges of the closed wingdefining an interior region, the at least one tail ejector being atleast partially disposed within the interior region; and first andsecond canard wings coupled to the fore portion and respectively coupledto the starboard side and port side, the canard wings configured todevelop boundary layers of ambient air flowing over the canard wingswhen the vehicle is in motion, the canard wings being respectivelylocated directly upstream of the first and second fore ejectors suchthat the first and second fore ejectors are fluidly coupled to theboundary layers.
 2. The vehicle of claim 1, wherein the first and secondcanard wings each have a leading edge, and the entirety of each of thefirst and second canard wings is rotatable about an axis orientedparallel to the leading edge.
 3. The vehicle of claim 1, wherein thefirst and second fore ejectors respectively comprise first and secondinlet portions, and the first and second fore ejectors are positionedsuch that the boundary layers are ingested by the inlet portions.
 4. Avehicle, comprising: a main body having a fore portion, a tail portion,a starboard side, a port side and a cockpit formed therein toaccommodate a human pilot; a first fluid generator coupled to the mainbody and producing a first fluid stream; at least one tail conduitfluidly coupled to the first generator; first and second fore ejectorscoupled to the fore portion and respectively coupled to the starboardside and port side, the fore ejectors respectively comprising an outletstructure out of which fluid flows at a predetermined adjustablevelocity; at least one tail ejector fluidly coupled to the at least onetail conduit and coupled to the tail portion, the at least one tailejector comprising an outlet structure out of which fluid from the atleast one tail conduit flows at a predetermined adjustable velocity; aprimary airfoil element coupled to the tail portion and comprising aclosed wing having a leading edge and a trailing edge, the leading andtrailing edges of the closed wing defining an interior region, the atleast one tail ejector being at least partially disposed within theinterior region; second and third fluid generators coupled to the mainbody and respectively producing a second fluid stream and a third fluidstream; and first and second fore conduits respectively fluidly coupledto the second and third generators, wherein the first and second foreejectors are respectively fluidly coupled to the first and second foreconduits and respectively receive the second and third fluid streams. 5.A vehicle, comprising: a main body having a fore portion, a tailportion, a starboard side, a port side and a cockpit formed therein toaccommodate a human pilot; a first fluid generator coupled to the mainbody and producing a first fluid stream; at least one tail conduitfluidly coupled to the first generator; first and second fore ejectorscoupled to the fore portion and respectively coupled to the starboardside and port side, the fore ejectors respectively comprising an outletstructure out of which fluid flows at a predetermined adjustablevelocity; at least one tail ejector fluidly coupled to the at least onetail conduit and coupled to the tail portion, the at least one tailejector comprising an outlet structure out of which fluid from the atleast one tail conduit flows at a predetermined adjustable velocity; anda primary airfoil element coupled to the tail portion and comprising aclosed wing having a leading edge and a trailing edge, the leading andtrailing edges of the closed wing defining an interior region, the atleast one tail ejector being at least partially disposed within theinterior region, wherein the first fluid stream produced by the firstgenerator is the sole means of propulsion of the vehicle.
 6. A vehicle,comprising: a main body having a fore portion, a tail portion, astarboard side, a port side and a cockpit formed therein to accommodatea human pilot; a first fluid generator coupled to the main body andproducing a first fluid stream; at least one tail conduit fluidlycoupled to the first generator; first and second fore ejectors coupledto the fore portion and respectively coupled to the starboard side andport side, the fore ejectors respectively comprising an outlet structureout of which fluid flows at a predetermined adjustable velocity; atleast one tail ejector fluidly coupled to the at least one tail conduitand coupled to the tail portion, the at least one tail ejectorcomprising an outlet structure out of which fluid from the at least onetail conduit flows at a predetermined adjustable velocity; and a primaryairfoil element coupled to the tail portion and comprising a closed winghaving a leading edge and a trailing edge, the leading and trailingedges of the closed wing defining an interior region, the at least onetail ejector being at least partially disposed within the interiorregion, wherein the first and second fore ejectors each have a leadingedge, and the entirety of each of the first and second fore ejectors isrotatable about an axis oriented parallel to the leading edge.
 7. Avehicle, comprising: a main body having a fore portion, a tail portion,a starboard side, a port side and a cockpit formed therein toaccommodate a human pilot; a first fluid generator coupled to the mainbody and producing a first fluid stream; at least one tail conduitfluidly coupled to the first generator; first and second fore ejectorscoupled to the fore portion and respectively coupled to the starboardside and port side, the fore ejectors respectively comprising an outletstructure out of which fluid flows at a predetermined adjustablevelocity; at least one tail ejector fluidly coupled to the at least onetail conduit and coupled to the tail portion, the at least one tailejector comprising an outlet structure out of which fluid from the atleast one tail conduit flows at a predetermined adjustable velocity; anda primary airfoil element coupled to the tail portion and comprising aclosed wing having a leading edge and a trailing edge, the leading andtrailing edges of the closed wing defining an interior region, the atleast one tail ejector being at least partially disposed within theinterior region, wherein the first and second fore ejectors areretractable into the main body during a cruise condition of the vehicle.8. A vehicle, comprising: a main body having a fore portion, a tailportion, a starboard side, a port side and a cockpit formed therein toaccommodate a human pilot; a first fluid generator coupled to the mainbody and producing a first fluid stream; at least one tail conduitfluidly coupled to the first generator; first and second fore ejectorscoupled to the fore portion and respectively coupled to the starboardside and port side, the fore ejectors respectively comprising an outletstructure out of which fluid flows at a predetermined adjustablevelocity; at least one tail ejector fluidly coupled to the at least onetail conduit and coupled to the tail portion, the at least one tailejector comprising an outlet structure out of which fluid from the atleast one tail conduit flows at a predetermined adjustable velocity; anda primary airfoil element coupled to the tail portion and comprising aclosed wing having a leading edge and a trailing edge, the leading andtrailing edges of the closed wing defining an interior region, the atleast one tail ejector being at least partially disposed within theinterior region, wherein the at least one tail ejector has a leadingedge, and the entirety of the at least one tail ejector is rotatableabout an axis oriented parallel to the leading edge.
 9. A vehicle,comprising: a main body having a fore portion, a tail portion, astarboard side, a port side and a cockpit formed therein to accommodatea human pilot; a first fluid generator coupled to the main body andproducing a first fluid stream; at least one tail conduit fluidlycoupled to the first generator; first and second fore ejectors coupledto the fore portion and respectively coupled to the starboard side andport side, the fore ejectors respectively comprising an outlet structureout of which fluid flows at a predetermined adjustable velocity; atleast one tail ejector fluidly coupled to the at least one tail conduitand coupled to the tail portion, the at least one tail ejectorcomprising an outlet structure out of which fluid from the at least onetail conduit flows at a predetermined adjustable velocity; and a primaryairfoil element coupled to the tail portion and comprising a closed winghaving a leading edge and a trailing edge, the leading and trailingedges of the closed wing defining an interior region, the at least onetail ejector being at least partially disposed within the interiorregion, wherein the tail ejector is controllably movable relative to theinterior region while the vehicle is in flight.
 10. A vehicle,comprising: a main body having a fore portion, a tail portion, astarboard side, a port side and a cockpit formed therein to accommodatea human pilot; a first fluid generator coupled to the main body andproducing a first fluid stream; at least one tail conduit fluidlycoupled to the first generator; first and second fore ejectors coupledto the fore portion and respectively coupled to the starboard side andport side, the fore ejectors respectively comprising an outlet structureout of which fluid flows at a predetermined adjustable velocity; atleast one tail ejector fluidly coupled to the at least one tail conduitand coupled to the tail portion, the at least one tail ejectorcomprising an outlet structure out of which fluid from the at least onetail conduit flows at a predetermined adjustable velocity; and a primaryairfoil element coupled to the tail portion and comprising a closed winghaving a leading edge and a trailing edge, the leading and trailingedges of the closed wing defining an interior region, the at least onetail ejector being at least partially disposed within the interiorregion, wherein: the fluid generator comprises a first region in whichthe fluid stream is at a low temperature and a second region in whichthe fluid stream is at a high temperature; the at least one fore conduitprovides fluid from the first region to the first and second foreejectors; and the at least one tail conduit provides fluid from thesecond region to the at least one tail ejector.
 11. A vehicle,comprising: a main body having a fore portion, a tail portion, astarboard side, a port side and a cockpit formed therein to accommodatea human pilot; a first fluid generator coupled to the main body andproducing a first fluid stream; at least one tail conduit fluidlycoupled to the first generator; first and second fore ejectors coupledto the fore portion and respectively coupled to the starboard side andport side, the fore ejectors respectively comprising an outlet structureout of which fluid flows at a predetermined adjustable velocity; atleast one propeller fluidly coupled to the at least one tail conduit andcoupled to the tail portion; a primary airfoil element comprising aclosed wing having a leading edge and a trailing edge, the leading andtrailing edges of the closed wing defining an interior region, the atleast one propeller being at least partially disposed within theinterior region; and first and second canard wings coupled to the foreportion and respectively coupled to the starboard side and port side,the canard wings configured to develop boundary layers of ambient airflowing over the canard wings when the vehicle is in motion, the canardwings being respectively located directly upstream of the first andsecond fore ejectors such that the first and second fore ejectors arefluidly coupled to the boundary layers.
 12. The vehicle of claim 11,wherein the first and second canard wings each have a leading edge, andthe entirety of each of the first and second canard wings is rotatableabout an axis oriented parallel to the leading edge.
 13. The vehicle ofclaim 11, wherein the first and second fore ejectors respectivelycomprise first and second inlet portions, and the first and second foreejectors are positioned such that the boundary layers are ingested bythe inlet portions.